Process for the manufacture of carboxylic acid and sulfonic acid chlorides

ABSTRACT

Aliphatic, cycloaliphatic, aromatic and heterocyclic carboxylic acid and sulfonic acid chlorides are prepared from the corresponding carboxylic and sulfonic acids and phosgene by reacting the salt-like addition compounds of the said carboxylic or sulfonic acids with N-alkyl-pyrrolidones or N,N-dialkylcarboxylic acid amides having at least 4 carbon atoms in the molecule in a polar, inert solvent with phosgene at a temperature below 0*C, at atmospheric pressure or elevated pressure, and completing the reaction by heating at a temperature of at most +30*C. The acid chlorides obtained are especially pure and without further isolation they can be used, for example, for the manufacture of polyamides.

llnited States Patent iooii Dec. 31, W74

[ PROCESS FOR THE MANUFACTURE OF CARBOXYLIC ACID AND SULFONIC ACID CHLORIDES [75] Inventor: Gunther Keil, Lorsbach/Taunus,

Germany [73] Assignee: Hoechst Aktiengesellschaft,

Frankfurt/Main, Germany [22] Filed: Aug. 16, 1973 [21] Appl. No.: 388,883

30 Foreign Application Priority Data Aug. 19, 1972 Germany 22408839 [52] US. CL... 260/25() R, 260/287 R, 260/294.8 F,

260/295.5 R, 260/326.l3 R, 260/543 R,

260/544 K [51} Int. Cl. C07c 51/58 [58] Field of Search 260/544 K, 543 R, 250,

260/244.8 F, 287 R, 295.5 R

[56] References Cited UNITED STATES PATENTS 2,888,486 5/l959 Gregory 260/543 R 3,706,794 12/1972 Homer 260/543 R Primary Examiner-Lorraine A. Weinberger Assistant ExaminerRichard D. Kelly Attorney, Agent, or Firm-Curtis, Morris & Safford [57] ABSTRACT Aliphatic, cycloaliphatic, aromatic and heterocyclic carboxylic acid and sulfonic acid chlorides are prepared from the corresponding carboxylic and sulfonic 5 Claims, N0 Drawings PROCESS FOR THE MANUFACTURE OF CARBOXYILIC ACID AND SULFONIC ACID CHLORIDES The present invention relates to a process for the manufacture of carboxylic and sulfonic acid chlorides of high purity by reacting phosgene at low temperature with salts of corresponding acids and dimethylacetamide, N-methylpyrrolidone, or other high molecular weight N,N-dialkylcarboxylic acid amides, optionally in the presence of suitable solvents.

It has been proposed to prepare chlorides of the aforesaid type, for example by reacting carboxylic or sulfonic acids with phosphorus trichloride, phosphorus oxichloride, phosphorus pentachloride or thionyl chloride. The reaction of the acids with phosgene has also been described in a plurality of publications. This reaction has the advantage that only gaseous by-products are formed, which can be readily absorbed or do not pollute the atmosphere. The reactions take place according to the following equations:

R co,H 0001 RCOCl HCl co R-SO3H cocr R so,c1 HCl co In Houben-Weyl, Methoden der organischen Chemie, volume IX, page 567 (l955) a process is described for reacting sulfonic acids or the alkali metal salts thereof with phosgene in an inert medium at 140 to 180C to obtain sulfonic acid chlorides. Fatty acid chlorides with long chains can be prepared from the corresponding fatty acids and phosgene at 140 to 160C (cf. Houben- Weyl, volume VIII, page 472 (1952).

US. Pat. No. 2,657,233 provides a process for the manufacture of dicarboxylic acid dichlorides from dicarboxylic acids and phosgene under a pressure above atmospheres gage and at temperatures in the range of from 100 to 250C.

British Specification No. 540,096 discloses the manufacture of carboxylic acid chlorides from carboxylic acids having at least 10 carbon atoms and phosgene at a temperature of at least 100C in the presence of 5% of tertiary amines.

US. Pat. No. 2,848,491 is concerned with the reaction of mono-carboxylic acids with phosgene at a temperature in the range of from room temperature to 200C, preferably 90 to 200C, in the presence of an anion exchanger.

US. Pat. No. 3,184,506 teaches that the continuous manufacture of carboxylic acid chlorides from carboxylic acids and phosgene is also possible at temperatures of from 50 to 125C in the presence of 0.05 to 5% by weight, preferably 0.1 to 1% by weight, of dimethyl formamide. This process is characterized inthat in the reaction zone an excess of carboxyl groups must always prevail as otherwise the complex compound of dimethyl formamideand phosgene decomposes and large amounts of tarry reaction products are formed.

It is the common feature of all the aforesaid processes that the reaction with phosgene is carried out at elevated temperature and partly at elevated pressure. It cannot be avoided that under these reaction conditions a series of secondary reactions take place. The reaction products obtained are thus contaminated and must be freed from the by-products simultaneously formed by expensive purification processes. In the temperature ranges required acid chlorides react, for example. with the acids used as starting products to yield acid anhydrides with separation of HCl. With the use of nitrogen-containing catalysts undefined and colored by-products are obtained, which, especially in the case of a discontinuous process, may cause the formation of tarry deposits in the reaction vessels. The formation of such by-products could be substantially avoided if the reaction could be carried out at a sufficiently low tem- I perature. In the known processes the reaction speed at low temperature is, however, so slow that an economic manufacture is not possible. i

It has now beenfound that chlorides or carboxylic and sulfonic acids can be obtained in simple manner and withhigh purity by reacting the salts of carboxylic acids or sulfonic acids and N,N-dimethyl acetamide, N-methyl-pyrrolidone, or other N,N-dialkyl carboxylic acid amides having at least 4 carbon atoms, optionally dissolved in acetonitrile, or other polar inert solvents, with phosgene at a temperature of from 20 to 0C and completing the reaction by heating at a temperature of at most +30C. The reaction takes place very quickly and with a high yield according to the following equations:

RCO2H-CH3CON(CH3)2 C0012 To prepare the salt-like compounds from carboxylic acids or sulfonic acids N,N-dimethyl acetamide, N-methyl-pyrrolidone, or other N,N-dialkyl carboxylic acid amides having at least 4 carbon atoms can be used, for example tetramethyl-urea, whereas the lowest representative of this class the N,N-dimethyl formamide is unsuitable because of the very low yield obtained therewith.

The salt-like compounds from the acids and dimethyl acetamide need not be prepared in a seperate reaction and isolated in substance. Preferably, equimolecular amounts of the components can be used in the phosgenation. The salts of carboxylic acids or sulfonic acids and dimethyl acetamide, N-methyl-pyrrolidone, or other higher N,N-dialkylcarboxylic acid amides are often sparinglysoluble only in the chosen solvent, but a very low solubility is already sufficient to start the reaction.

Besides acetonitrile, other polar solvents or diluents that can be mixed with water or are readily soluble in water can be used, provided that they are inert to the reactants at the reaction temperatures. Solvents of this type are, for example, propionitrile, tetrahydrofurane, glycol dimethyl ether, and diglycol dimethyl ether.

The ratio of amide salt to acetonitrile or another polar diluent can vary in the range of from 1 0.8 to l 2.0, preferably 1 1.2 to 1 1.6 parts by weight. It is also possible to operate without a special diluent, provided that an excess of the N-alkyl-pyrrolidone or, N,N-dialkyl-carboxylic acid amide required for the forf' mation of the salt-like addition compounds is used.

When carrying out the process of theinventionthe reaction temperatures should be kept so low that no secondary reactions of the phosgene or the acidchlorides with the nitrogen-containing salt forming agents or the free acid may occur. Thereaction temperatures are in the range of from 3(i" to +30C,preferably, however from 20 to +20C. According to a preferred embodiment of the process of the invention phosgene is introduced at low temperature, for example about 15C, and the reaction is then completed by heating, for example to 20C. At temperatures exceeding 30C continuouslydecreasing yields of the desired acid chlorides are obtained.

For' each equivalent of the carboxyl group or sulfonic acid group 1.0 to 1.5 equivalents, preferably 1.1 to 1.2

equivalents of phosgene are used. The phosgene can be added in dosed quantities at atmospheric pressure or at elevated pressure. Sulfonic acids often contain crystal water, but the hydrates may also be used if one mole of phosgene and two moles of the nitrogen containing salt forming agent are additionally used tobind one mole of crystal water.

With discontinuous performance of the process of the invention the termination of the reaction can be perceived by the end of the CO separation. When a suspension is used for phosgenation, the formation of a clear solution likewise indicates the end of the reation. In the latter case, it must be kept in mind, however, that following the reaction proper there may often occur a precipitaion of hydro-chlorides of dimethyl acetamide or the other corresponding compounds. Depending on the introduction rate of the phosgene, the reaction time is in the range of from 1 to about hours.

Prior to working up the reaction mixture by distillation it is necessary to remove the formed hydrochlorides of the nitrogen containing compounds, for example of dimethyl acetamide, as these substances react with the acid chlorides at elevated temperature. To remove the hydrochlorides the reaction mixture can be diluted with a non polar solvent for example benzene, whereupon the hydrochloride crystallizes out and can be filtred off. Thus, the compounds used as salt forming agents and catalysts can be recovered. If necessary, last traces of the amide hydrochlorides can be eliminated by rapidly washing with cold water the reaction solution diluted with an inert solvent.

The reaction solutions obtained in the process of the invention can be directly used for further reactions without further treatment or purification of the acid chlorides. It is thus possible to produce unsaturated and/or temperature sensitive acid chlorides and directly to use the reaction solutions obtained for further reactions. The reaction solutions can be reacted, for example, with amines, alcohols or phenols. They are also suitable for the manufacture of polyamides, for example by the process disclosed in German Pat. No. 1,420,681, without isolating the acid chlorides obtained.

1n the process of the present invention the following carboxylic and sulfonic acids can be used:

1. aliphatic, cycloaliphatic, aromatic and heterocyclic mono-, diand polycarboxylic acids possibly carrying substituents which do not react at the chosen reaction temperatures with the acid chlorides or phosgene, such as, for exammple, acetic acid, chloroacetic acid, propionic acid, acrylic 5 acid, butyric acid, crotonic acid, cyclohexanecarboxylic acid, adipic acid, sebacic acid, cyclohexane-l,4 dicarboxylic acid, benzoic acid, toluylic acid, naphthalene-carboxylic acids, halogenated benzoic acids, isophthalic acid, tereph- 0 thalic acid, trimellitic acid, nicotinic acid, quinoline-carboxylic acid, indole-3-carboxylic acid, pyrazine-2,3-dicarboxylic acid;

2. aliphatic, cycloaliphatic and aromatic monoand disulfonic acids possibly containing further substituents which sre inert to sulfonic acid chlorides and phosgene at low temperatures, for example methane-sulfonic acid, ethane-disulfonic acid, butane-sulfonic acid, B-chlorethane-sulfonic acid, cyclohexane-sulfonic acid, benzene-sulfonic acids, toluene-sulfonic acids, p-chloro-benzene-sulfonic acids,- naphthalene-sulfonic acids, benzene-1,3-disulfonic acid, naphthalenedisulfonic acids, pyridine-3-sulfonic acid.

The following examples illustrate the invention, the parts and percentages being by weight unless otherwise stated.

EXAMPLE 1 61 Parts of benzoic acid were dissolved in a mixture of 49.5 parts of N-methyl-pyrrolidone and 200 parts by volume of aceto-nitrile. The solution was cooled to 15C with the exclusion of moisture and at a temperature in a range of from to l5C 60 parts of phosgene were introduced within about 30 minutes. When the introduction was terminated, the solution was stirred for about minutes at 15C. Next, the reaction mixture was heated to about +C within the course of 2 hours. During this period of time considerable amounts of CO were split off. The reaction mixture was stirred for a further hour at 20C and diluted with 2,000 parts by volume of benzene or toluene. The solution was filtred, rapidly washed with a total amount of 500 parts by volume of ice-water, dried and concentrated. At a temperature of 64 65C under 12 mm Hg 59.7 parts (85 of the theory) of benzoyl chloride were obtained by distillation of the residue.

EXAMPLE 2 166 parts of isophthalic acid were mixed with 174 parts of N,N-dimethyl acetamide and 500 parts by volume of acetonitrile. By heating at about C a homogeneous solution was obtained. On cooling the salt of 1 mole isophthalic acid and 2 moles of dimethyl acetamide crystallized out. At -10C 220 parts of phosgene were introduced into the mixture with the exclusion of moisture within the course of 1 hour. The mixture was then heated to +20C during the course of 1 hour. A yellowish solution formed with splitting off of CO Stirring of the solution was continued for 2 hours at +20C, whereupon it was diluted with 4,000 parts by volume of benzene. The reaction mixture was allowed to stand for a short while, the separated dimethyl acetamide hydrochloride was separated and the acid chloride solution was rapidly washed with about 1,000 parts by volume of ice-water. The solution was dried, concentrated and the residue subjected to fractional distillation. At 102 104C under 1.5 mm Hg 191.5 parts (94 of the theory) of isophthaloyl chloride distilled off.

When the reaction was carried out at +70C, the yield of isophthaloyl chloride was only 45.5 of the theory.

EXAMPLE 3 1 Parts of phosgene were introduced within 1 hour at 12C into a mixture of 83 parts of isophthalic acid,

EXAMPLE 4 83 Parts of isophthalic acid were dissolved in 500 parts by volume of dimethyl acetamide by heating to 70C. The colorless substance which crystallized out on cooling to C was filtered off with suction, washed with ether and carefully dried. 94.8 Parts (55.8 of

the theory) of a salt of 1 mole of isophthalic acid and acid, 87 parts of dimethyl acetamide and 300 parts by volume of acetonitrile. The reaction mixture was heated to C and stirred at that temperature for 1 hour. The mixture was then diluted with 2,000 parts by volume of benzene and the precipitated dimethyl acetamide hydrochloride was filtred off. The filtrate was subjected to fractional distillation by means of a column having a good separation power. 97.6 parts (66.6 of the theory) cyclohexane-carboxylic acid chloride were obtained at 61C under 7 mm Hg.

EXAMPLE 8 95.1 Parts of p-toluene-sulfonic acid monohydrate were dissolved in a mixture of 130.5 parts of N,N- dimethyl acetamide and 300 parts by volume of acetonitrile, the solution was cooled to 10C and at that temperature 110 parts of phosgene were introduced 2 moles of dimethyl acetamide having the summation formula C H N O were obtained. The decomposition point of the compound was found to be 82C.

A mixture of 170 parts of the salt and 200 parts by volume of acetonitrile was reacted at 10C with llO parts of phosgene. After working up under the conditions of the preceding examples, 85.6 parts (84 of r the theory) of isophthaloyl chloride were obtained.

EXAMPLE 5 and diluted with 1,500 parts by volume of benzene. The

benzenic solution was rapidly washed with icewater, dried, concentrated and the residue was distilled. At 129 130C under 10 mm Hg 87.2 parts (86 of the theory) of terephthaloyl chloride melting at 83C were obtained.

EXAMPLE 6 1n the manner described above a mixture of 83 parts of terephthalic acid, 87 parts of dimethyl acetamide and 300 parts by volume of acetonitrile was reacted with 110 parts of phosgene. After termination of the reaction a solution of 87 parts of dimethyl acetamide in 100 parts of methanol was dropped into the reaction mixture. The temperature rose to C. After having been allowed to stand for 1 hour at about 25C, the reaction mixture was poured on ice. The crystalline pre cipitate was filtred off with suction, washed and dried. 63 Parts (65 of the 'theory) of terephthalic acid dimethyl ester melting at 141C were obtained.

EXAMPLE 7 118 Grams of phosgene were introduced at 13C into a mixture of 128 parts of cyclohexane-carboxylic during the course of about 1 hour. The mixture was stirred for 30 minutes at 10C, the temperature was rised to +20C within 2 hours and the mixture kept at that temperature for another 2 hours. Considerable amounts of CO separated. The mixture was diluted with benzene, the dimethyl acetamide hydrochloride was filtred off, the filtrate was rapidly washed with a small amount of icewater and concentrated. The residue was distilled under reduced pressure. 88.6 Parts (93 of the theory) of p-toluene-sulfonic acid chloride melting at 69C distilled over at 135 136C under 10 mm Hg.

When the reaction solution diluted with benzene was not washed with icewater, the yield of p-toluenesulfonic acid dichloride amounted to 86 of the theory.

EXAMPLE 9 EXAMPLE 10 25 Parts of p-toluene-sulfonic acid monohydrate were dissolved in 100 parts by volume of N,N-dimethyl acetamide and benzene was added to the solution until it became turbid. The separating crystals were filtred off with suction, washed with benzene and dried. 22.5 Parts (62 of the theory) of colorless crystals were obtained which started to decompose at 73C. It was the p-toluene-sulfonic acid dimethyl acetamide salt of the summation formula C H NO S.

A mixture of 129.5 parts of the salt with 200 parts by volume of acetonitrile was reacted at 12C with phosgene in the manner described above. After the usual working up, 75 parts (79 of the theory) of p-toluenesulfonic acid chloride were obtained.

EXAMPLE 1 1 73 Parts of adipic acid, 87 parts of N,N-dimethyl acetamide and 200 parts by volume of acetonitrile were reacted at 12C with 1 12 grams of phosgene. The reaction mixture was allowed to warm up to +21C whereby CO was split off. The mixture was diluted with 2,000 parts by volume of benzene and the dimethyl acetamidehydrochloride was filtred off with suction. The filtrate was concentrated in a thin layer evaporator. From themes-Hue a further portion of dimethyl acetamide hydrochloride separated, which was filtred off. The filtrate was distilled and 52.1 parts (57 of the theory) of adipic acid dichloride were obtained at a boiling pointof 97C under 2 mm Hg.

EXAMPLE 12 86 Parts of crotonic acid, 87 parts of dimethyl acetamide and 250 parts by volume of acetonitrile were reacted at C with 108 grams of phosgene. The reaction mixture was heated to +C whereby CO was split off. The mixture was stirred for about 2 hours at +20C, diluted with 2,000 parts by volume of benzene and the dimethyl acetamide hydrochloride was filtered off with suction. The filtrate was washed with icewater, dried and concentrate. By distillation of the residue 58.5 parts (56 of the theory) of crotonic acid chloride were obtained at 124C under 760 mm Hg.

EXAMPLE 13 72 Parts of acrylic acid were dissolved in 87 parts of EXAMPLE 14 During the course of 90 minutes a solution of 123 grams of pyridine-3-carboxylic acid (nicotinic acid) in 600 milliliters of dimethyl acetamide was reacted at l0C with 120 grams of phosgene. The reaction was completed by heating the reaction mixture to +20C for a short while. The reaction solution was againcooled to l0C and 219 grams of diethyl amine were dropped in at that temperature within 20 minutes. The reaction mixture was heated at +20C and allowed to stand for some hours at that temperature. The dark brown reaction solution was poured into water, sodium hydroxide was added and the mixture extracted with benzene. The benzene phase was dried and concentrated. By fractional distillation 125.5 grams of nicotinic acid diethyl amide were obtained in the form of a yellowish oil at a temperature of 126C under 0.8 mm Hg.

What is claimed is:

1. A process for the manufacture of a carboxylic acid chloride from the corresponding carboxylic acid and phosgene, which comprises reacting the salt-like addition compound of an aliphatic, cycloaliphatic, aromatic or heterocyclic carboxylic acid having 1 or 2 hetero nitrogen atoms with an N-alkyl-pyrrolidone or an N,N-dialkyl-carboxylic acid amide having at least 4 carbon atoms in the molecule, in a polar, inert solvent present in weight ratio of 0.8:1 to 20:1 to said salt like addition compound, with 1.0 to 1.5 molar equivalents of phosgene based upon said carboxylic acid at a temperature from 30C to +30C, at atmospheric pressure or elevated pressure and completing the reaction by heating the reaction mixture to at most +30C.

2. The process of claim 1, wherein the reaction temperature is in the range of from 20 to +20C.

3. The process of claim 1, wherein the inert solvent is acetonitrile.

4. The process of claim 1, wherein an excess of the N-alkyl-pyrrolidone or N,N-dialkyl-carboxylic acid amide used for the formation of the salt-like addition compound is used as inert solvent.

5. The process of claim 1, wherein N-methylpyrrolidone or N,N-dimethyl acetamide is used. 

1. A PROCESS FOR THE MANUFACTURE OF A CARBOXYLIC ACID CHLORIDE FROM THE CORRESPONDING CARBOXYLIC ACID AND PHOSGENE, WHICH COMPRISES REACTING THE SALT-LIKE ADDITION COMPOUND OF AN ALIPHATIC, CYCLOALIPHATIC, AROMATIC OR HETEROCYCLIC CARBOXYLIC ACID HAVING 1 OR 2 HETERO NITROGEN ATOMS WITH AN N-ALKYLPYRROLIDONE OR AN N,N-DIALKYL-CARBOXYLIC ACID AMIDE HAVING AT LEAST 4 CARBON ATOMS IN THE MOLECULE, IN A POLAR, INERT SOLVENT PRESENT IN WEIGHT RATIO OF 0.8:1 TO 2.0:1 TO SAID SALT LIKE ADDITION COMPOUND, WITH 1.0 TO 1.5 MOLAR EQUIVALENTS OF PHOSGENE BASED UPON SAID CARBOXYLIC ACID AT A TEMPERATURE FROM -30*C TO +30*C, AT ATMOSPHERIC PRESSURE OR ELEVATED PRESSURE AND COMPLETING THE REACTION BY HEATING THE REACTION MIXTURE TO AT MOST +30*C.
 2. The process of claim 1, wherein the reaction temperature is in the range of from -20 to +20*C.
 3. The process of claim 1, wherein the inert solvent is acetonitrile.
 4. The process of claim 1, wherein an excess of the N-alkyl-pyrrolidone or N,N-dialkyl-carboxylic acid amide used for the formation of the salt-like addition compound is used as inert solvent.
 5. The process of claim 1, wherein N-methyl-pyrrolidone or N,N-dimethyl acetamide is used. 